1. Technical Field
The present invention relates to a motor control system including a drive motor, an auxiliary motor, and a controller. The present invention also relates to a control system for a motor-driven vehicle including the drive motor and the auxiliary motor, a drive motor controller for controlling the drive motor, an auxiliary motor controller for controlling the auxiliary motor, and a main controller.
2. Related Art
A mower vehicle including a mower which is a working implement that is driven to perform mowing, is conventionally known. With respect to such a mower vehicle, it is conceivable to configure a motor-driven vehicle where left and right wheels, which are main driving wheels, are each driven by a drive motor which is a separate or a common electric motor, and where the mower is driven by a mower motor which is an electric motor.
In the specification of US 2009/0069964A1, there is described a mower vehicle including a drive motor which is a common electric motor that drives left and right wheels, a steering wheel, and a mower motor. This mower vehicle includes a drive controller to be connected to the drive motor, and a mower controller to be connected to the mower motor and the drive controller. The drive controller stores instructions that can be carried out by a computer, and such an instruction is for performing a process of stopping electric power supply to the mower motor and reducing the vehicle speed when battery voltage reaches a specific minimum voltage, for example.
Furthermore, in the specification of U.S. Pat. No. 5,502,957, there is described a mower vehicle where a control unit stops the mower when battery voltage reaches or falls below a certain voltage and the amount of charge reaches or falls below a certain amount of charge. The specification of U.S. Pat. No. 5,502,957 also describes stopping a deck motor in a case where a thermistor detects high temperature. Additionally, as related art documents related to the present invention, there are, in addition to the specification of US 2009/0069964A1 and the specification of U.S. Pat. No. 5,502,957, the specification of U.S. Pat. No. 8,055,399B2, the specification of US2009/0065273A1, the specification of US 2009/0201650A1, and the specification of US2005/0126145A1.
According to an electric motor-driven vehicle including a drive motor and an auxiliary motor, electric power is supplied to the drive motor and the auxiliary motor from a battery which is an electric power storage unit. In this case, electric power supply to each motor may stop when SOC (state of charge), which is the amount of charge of the battery, reaches or falls below a certain threshold. In this case, the vehicle cannot be driven by the drive motor, and it becomes difficult to make the vehicle move on its own to a desired location to pull over, such as a repair garage. Accordingly, it is desired to provide a driver a chance to pull over when the SOC of the battery is reduced, instead of immediately disabling travelling, and to increase the travelling range after providing the chance. The configurations described in the specification of US2009/0069964A1, the specification of U.S. Pat. No. 5,502,957, the specification of U.S. Pat. No. 8,055,399B2, the specification of US2009/0065273 A1, the specification of US2009/0201650A1, and the specification of US2005/0126145A1 do not disclose means for providing a driver a chance to pull over when the SOC is reduced, and for increasing the travelling range after providing the chance.
Also, according to a motor-driven vehicle including a drive motor for driving a driving wheel, and an auxiliary motor for driving a working implement or the like, there are cases where the drive motor and the auxiliary motor are driven by a controller. Also, electric power is supplied to the controller from a battery which is an electric power storage unit. In this case, switching between electric power supply from the battery to the controller and interruption of the electric power supply may be performed according to ON/OFF of a key switch, which is a manual switch to be operated by the driver. However, there is a possibility that the driver turns off the key switch by mistake while driving the vehicle or a device to be driven by a motor. If the controller is immediately turned off in this state, because at least one motor is not controlled while the motor is rotating, there possibly arises a situation which is not desirable with respect to the durability of the motor or a part such as an inverter connected to the motor.
Moreover, with a motor-driven vehicle including a drive motor and an auxiliary motor, in a case where at least one of the drive motor and the auxiliary motor is overloaded, it is desired to swiftly remove the overload and to protect the motor. The specifications of US2009/0069964A1, the specification of U.S. Pat. No. 5,502,957, the specification of U.S. Pat. No. 8,055,399B2, the specification of US2009/0065273A1, the specification of US 2009/0201650A1, and the specification of US2005/0126145A1 do not disclose means for solving such problems.